From 52c8ac90eabf94cae576e916cc087db6739a7697 Mon Sep 17 00:00:00 2001
From: Andrew Wang <wang@apache.org>
Date: Tue, 7 Oct 2014 14:57:03 -0700
Subject: [PATCH] HADOOP-11172. Improve error message in Shell#runCommand on
 OutOfMemoryError. (Yongjun Zhang via wang)

(cherry picked from commit 4b2834898cbcc66ffbf01b2fb10375e79a50d538)
---
 hadoop-common-project/hadoop-common/CHANGES.txt           | 3 +++
 .../src/main/java/org/apache/hadoop/util/Shell.java       | 8 +++++++-
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/hadoop-common-project/hadoop-common/CHANGES.txt b/hadoop-common-project/hadoop-common/CHANGES.txt
index f90edb29dcc..4e7627f3f48 100644
--- a/hadoop-common-project/hadoop-common/CHANGES.txt
+++ b/hadoop-common-project/hadoop-common/CHANGES.txt
@@ -14,6 +14,9 @@ Release 2.7.0 - UNRELEASED
     HDFS-7186. Document the "hadoop trace" command. (Masatake Iwasaki via Colin
     P. McCabe)
 
+    Improve error message in Shell#runCommand on OutOfMemoryError.
+    (Yongjun Zhang via wang)
+
   OPTIMIZATIONS
 
   BUG FIXES
diff --git a/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/Shell.java b/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/Shell.java
index fcdc021f4e4..b78d791d592 100644
--- a/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/Shell.java
+++ b/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/Shell.java
@@ -519,7 +519,13 @@ public void run() {
     };
     try {
       errThread.start();
-    } catch (IllegalStateException ise) { }
+    } catch (IllegalStateException ise) {
+    } catch (OutOfMemoryError oe) {
+      LOG.error("Caught " + oe + ". One possible reason is that ulimit"
+          + " setting of 'max user processes' is too low. If so, do"
+          + " 'ulimit -u <largerNum>' and try again.");
+      throw oe;
+    }
     try {
       parseExecResult(inReader); // parse the output
       // clear the input stream buffer